diff --git a/linux-2.6-xen-sparse/drivers/xen/pciback/conf_space.c b/linux-2.6-xen-sparse/drivers/xen/pciback/conf_space.c
index 9eee88cd07..14e69adeec 100644
--- a/linux-2.6-xen-sparse/drivers/xen/pciback/conf_space.c
+++ b/linux-2.6-xen-sparse/drivers/xen/pciback/conf_space.c
@@ -357,7 +357,7 @@ int pciback_config_add_field_offset(struct pci_dev *dev,
 	void *tmp;
 
 	/* silently ignore duplicate fields */
-	if (pciback_field_is_dup(dev, field->offset))
+	if (pciback_field_is_dup(dev, field->offset + offset))
 		goto out;
 
 	cfg_entry = kmalloc(sizeof(*cfg_entry), GFP_KERNEL);